skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Crystallization Mechanism and Charge Carrier Transport in MAPLE-Deposited Conjugated Polymer Thin Films

Abstract

Although spin casting and chemical surface reactions are the most common methods used for fabricating functional polymer films onto substrates, they are limited with regard to producing films of certain morphological characteristics on different wetting and nonwetting substrates. The matrix-assisted pulsed laser evaporation (MAPLE) technique offers advantages with regard to producing films of different morphologies on different types of substrates. Here, we provide a quantitative characterization, using X-ray diffraction and optical methods, to elucidate the additive growth mechanism of MAPLE-deposited poly(3-hexylthiophene) (P3HT) films on substrates that have undergone different surface treatments, enabling them to possess different wettabilities. We show that MAPLE-deposited films are composed of crystalline phases, wherein the overall P3HT aggregate size and crystallite coherence length increase with deposition time. A complete pole figure constructed from X-ray diffraction measurements reveals that in these MAPLE-deposited films, there exist two distinct crystallite populations: (i) highly oriented crystals that grow from the flat dielectric substrate and (ii) misoriented crystals that preferentially grow on top of the existing polymer layers. The growth of the highly oriented crystals is highly sensitive to the chemistry of the substrate, whereas the effect of substrate chemistry on misoriented crystal growth is weaker. The use of a self-assembledmore » monolayer to treat the substrate greatly enhances the population and crystallite coherence length at the buried interfaces, particularly during the early stage of deposition. Furthermore, the evolution of the in-plane carrier mobilities during the course of deposition is consistent with the development of highly oriented crystals at the buried interface, suggesting that this interface plays a key role toward determining carrier transport in organic thin-film transistors.« less

Authors:
ORCiD logo [1];  [2];  [2];  [3];  [4]; ORCiD logo [5]
  1. Univ. of Michigan, Ann Arbor, MI (United States); The Univ. of Chicago, Chicago, IL (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Univ. of Michigan, Ann Arbor, MI (United States)
  4. Univ. of Tennessee, Knoxville, TN (United States)
  5. Univ. of Michigan, Ann Arbor, MI (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
National Science Foundation (NSF), Directorate for Mathematical and Physical Sciences Division of Materials Research (MPS-DMR); Vietnam Education Foundation; University of Michigan; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1415483
Grant/Contract Number:
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 9; Journal Issue: 51; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; MAPLE; X-Ray diffraction; conjugated polymers; crystallization; structure-transport relationship

Citation Formats

Dong, Ban Xuan, Strzalka, Joseph, Jiang, Zhang, Li, Huanghe, Stein, Gila E., and Green, Peter F. Crystallization Mechanism and Charge Carrier Transport in MAPLE-Deposited Conjugated Polymer Thin Films. United States: N. p., 2017. Web. doi:10.1021/acsami.7b13609.
Dong, Ban Xuan, Strzalka, Joseph, Jiang, Zhang, Li, Huanghe, Stein, Gila E., & Green, Peter F. Crystallization Mechanism and Charge Carrier Transport in MAPLE-Deposited Conjugated Polymer Thin Films. United States. doi:10.1021/acsami.7b13609.
Dong, Ban Xuan, Strzalka, Joseph, Jiang, Zhang, Li, Huanghe, Stein, Gila E., and Green, Peter F. Thu . "Crystallization Mechanism and Charge Carrier Transport in MAPLE-Deposited Conjugated Polymer Thin Films". United States. doi:10.1021/acsami.7b13609.
@article{osti_1415483,
title = {Crystallization Mechanism and Charge Carrier Transport in MAPLE-Deposited Conjugated Polymer Thin Films},
author = {Dong, Ban Xuan and Strzalka, Joseph and Jiang, Zhang and Li, Huanghe and Stein, Gila E. and Green, Peter F.},
abstractNote = {Although spin casting and chemical surface reactions are the most common methods used for fabricating functional polymer films onto substrates, they are limited with regard to producing films of certain morphological characteristics on different wetting and nonwetting substrates. The matrix-assisted pulsed laser evaporation (MAPLE) technique offers advantages with regard to producing films of different morphologies on different types of substrates. Here, we provide a quantitative characterization, using X-ray diffraction and optical methods, to elucidate the additive growth mechanism of MAPLE-deposited poly(3-hexylthiophene) (P3HT) films on substrates that have undergone different surface treatments, enabling them to possess different wettabilities. We show that MAPLE-deposited films are composed of crystalline phases, wherein the overall P3HT aggregate size and crystallite coherence length increase with deposition time. A complete pole figure constructed from X-ray diffraction measurements reveals that in these MAPLE-deposited films, there exist two distinct crystallite populations: (i) highly oriented crystals that grow from the flat dielectric substrate and (ii) misoriented crystals that preferentially grow on top of the existing polymer layers. The growth of the highly oriented crystals is highly sensitive to the chemistry of the substrate, whereas the effect of substrate chemistry on misoriented crystal growth is weaker. The use of a self-assembled monolayer to treat the substrate greatly enhances the population and crystallite coherence length at the buried interfaces, particularly during the early stage of deposition. Furthermore, the evolution of the in-plane carrier mobilities during the course of deposition is consistent with the development of highly oriented crystals at the buried interface, suggesting that this interface plays a key role toward determining carrier transport in organic thin-film transistors.},
doi = {10.1021/acsami.7b13609},
journal = {ACS Applied Materials and Interfaces},
number = 51,
volume = 9,
place = {United States},
year = {Thu Nov 23 00:00:00 EST 2017},
month = {Thu Nov 23 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on November 23, 2018
Publisher's Version of Record

Citation Metrics:
Cited by: 1work
Citation information provided by
Web of Science

Save / Share:
  • The morphological structure of poly(3-hexylthiophene) (P3HT) thin films deposited by both Matrix Assisted Pulsed Laser Evaporation (MAPLE) and solution spin-casting methods are investigated. We found that the MAPLE samples possessed a higher degree of disorder, with random orientations of polymer crystallites along the side-chain stacking, π-π stacking, and conjugated backbone directions. Furthermore, the average molecular orientations and relative degrees of crystallinity of MAPLE-deposited polymer films are insensitive to the chemistries of the substrates onto which they were deposited; this is in stark contrast to the films prepared by the conventional spin-casting technique. In spite of the seemingly unfavorable molecular orientations andmore » the highly disordered morphologies, the in-plane charge carrier transport characteristics of the MAPLE samples are comparable to those of spin-cast samples, exhibiting similar transport activation energies (56 meV versus 54 meV) to those reported in the literature for high mobility polymers.« less
  • In this work, poly(3-hexylthiophene) (P3HT) films prepared using the matrix-assisted pulsed laser evaporation (MAPLE) technique are shown to possess morphological structures that are dependent on molecular weight (MW). Specifically, the structures of low MW samples of MAPLE-deposited film are composed of crystallites/aggregates embedded within highly disordered environments, whereas those of high MW samples are composed of aggregated domains connected by long polymer chains. Additionally, the crystallite size along the side-chain (100) direction decreases, whereas the conjugation length increases with increasing molecular weight. This is qualitatively similar to the structure of spin-cast films, though the MAPLE-deposited films are more disordered. In-planemore » carrier mobilities in the MAPLE-deposited samples increase with MW, consistent with the notion that longer chains bridge adjacent aggregated domains thereby facilitating more effective charge transport. The carrier mobilities in the MAPLE-deposited simples are consistently lower than those in the solvent-cast samples for all molecular weights, consistent with the shorter conjugation length in samples prepared by this deposition technique.« less
  • In this work, poly(3-hexylthiophene) (P3HT) films prepared using the matrix-assisted pulsed laser evaporation (MAPLE) technique are shown to possess morphological structures that are dependent on molecular weight (MW). Specifically, the structures of low MW samples of MAPLE-deposited film are composed of crystallites/aggregates embedded within highly disordered environments, whereas those of high MW samples are composed of aggregated domains connected by long polymer chains. Additionally, the crystallite size along the side-chain (100) direction decreases, whereas the conjugation length increases with increasing molecular weight. This is qualitatively similar to the structure of spin-cast films, though the MAPLE-deposited films are more disordered. In-planemore » carrier mobilities in the MAPLE-deposited samples increase with MW, consistent with the notion that longer chains bridge adjacent aggregated domains thereby facilitating more effective charge transport. The carrier mobilities in the MAPLE-deposited simples are consistently lower than those in the solvent-cast samples for all molecular weights, consistent with the shorter conjugation length in samples prepared by this deposition technique.« less